1. Field of the Invention
The present invention relates to an infrared cut filter and an imaging apparatus in which an infrared cut filter is used.
2. Description of the Related Art
A semiconductor solid-state imaging device such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) is built in imaging apparatus such as digital cameras. The sensitivity of these solid-state imaging devices extends from a visible spectrum range to an infrared spectrum range. For this reason, an infrared cut filter for shielding infrared light is provided between an imaging lens system and a solid-state imaging device in the imaging apparatus. The infrared cut filter enables calibrating the sensitivity of the solid-state imaging device to approximate the spectral sensitivity of human beings.
Infrared cut filters used in the related art include those manufactured by forming an infrared reflecting layer including a dielectric multilayer film on a resin substrate (see, for example, patent document 1).
[patent document 1] JP2005-338395
However, an infrared reflecting layer including a dielectric multilayer has incident angle dependence in which infrared shielding property varies depending on the incident angle. Therefore, the central part of an image capturing light transmitted through the infrared reflecting layer may look different in color from the periphery thereof.
Also, an infrared cut filter is required to have high abrasion resistance and environmental resistance because it is provided in front of a solid-state imaging device.